This invention relates to fuel systems and, more particularly, to a circuit for delivery of a cryogen in such systems.
Heretofore in cryogenic circuits involving the customary liquid and vapor phase operating modes, it has been customary to incorporate a solenoid valve for the liquid portion of a circuit and a second valve for the vapor side of the circuit with said valves being triggered by a pressure switch which is controlled by the particular operating mode. Generally, with relatively low pressure the pressure switch would cause energization of the solenoid valve in the liquid portion of the circuit for permitting liquid flow, and at a relatively elevated pressure the switch would cause energization of the other solenoid valve so as to allow for vapor phase flow. One of the most serious drawbacks to this earlier effort was that often the vapor phase flow alone did not provide adequate supply flow and since the solenoids were mutually independent or isolated, there would occur systematically supply line starvation during the vapor phase flow. Another earlier effort constituted a system having provision for liquid withdrawal only for the storage tank, there being no control valves other than safety relief valves. In systems of the present invention for effective operation it is requisite that there be means for permitting both vapor phase flow and liquid phase flow and concurrent flow of both vapor and liquid to meet high supply demands.
Therefore, it is an object of the present invention to provide a cryogenic circuit which is adapted to uniquely permit liquid phase flow simultaneously with vapor phase flow to meet high supply demands.
It is another object of the present invention to provide a cryogenic circuit which operates in an automatic fashion under fluid pressure so that the provision of liquid to the flow path during the vapor phase operating mode is brought about through a most reliable and yet simple operation which is devoid of pressure switches, solenoid valves, and the like.
It is another object of the present invention to provide a cryogenic circuit of the type stated wherein the liquid phase and vapor phase flows are fed through a common conduit to a feed or supply line so that the said phases are not isolated.
It is another object of the present invention to provide a control flow valve for use in a cryogenic system which is adapted for connection to both a source of vapor and source of liquid and incorporating unique valve means for allowing individual or combined flow therethrough responsive to pneumatic forces.
It is a further object of the present invention to provide a valve of the character stated which contains a single outlet orifice for both liquid phase and the vapor phase.
It is a further object of the present invention to provide a valve of the character stated which embodies a valve arrangement adapted under one set of circumstances to operate as a control valve and under other conditions to operate as a customary check valve.
It is a still further object of the present invention to provide a system of the character stated which contains a limited number of components which are of sturdy wear-resistant construction; which system is durable and reliable is usage; and which is both economical in manufacture, as well as in operation.